How can I set autoincrement format to 0001 in MySQL?

Question

How can I make MySQL auto increment in 4 digit format?

So instead of \'1\' make \'0001\'?

Answer 1

MySQL supports ZEROFILL on integer columns:

mysql> create table foo (the_key int unsigned zerofill not null 
       auto_increment primary key);
Query OK, 0 rows affected (0.21 sec)

mysql> insert into foo SET the_key = Null;
Query OK, 1 row affected (0.00 sec)

...

mysql> insert into foo SET the_key = Null;
Query OK, 1 row affected (0.00 sec)

mysql> select * from foo;
+------------+
| the_key    |
+------------+
| 0000000001 |
| 0000000002 |
| 0000000003 |
| 0000000004 |
| 0000000005 |
| 0000000006 |
| 0000000007 |
| 0000000008 |
+------------+
8 rows in set (0.00 sec)

You may need to look into using a smallint (5 digits), or trimming/padding.